The present invention relates to a novel fibrous assembly of a peptide lipid or, more particularly, to an assembly of fibers formed from a metal salt of a self-assembling bola-form peptide lipid having two oligo-L-valine residues or oligo-D-valine residues at both molecular terminals as well as to a method for the preparation of such a fibrous assembly.
As is well known, fibrous assemblies of a peptide lipid are widely employed in many applications, besides the applications as a drug delivery system or an adsorbent, in the fields of medical and pharmaceutical sciences as a bioadaptable material, in the fields of electronic and information-processing technologies as a material of microelectronic parts, in the fields of food industries, agriculture, forestry and fiber industries as an emulsifying agent, stabilizer, dispersing agent or moisturizing agent and so on.
In the prior art, spherical assemblies obtained from a natural phospholipid or so-called liposomes are known among molecular aggregates formed from a phospholipid. Such a spherical assembly is usually prepared by the thin-film method, thermal dispersion method, cholic acid method or reversed-layer evaporation method (see, for example, "Seitaimaku Jikkenhou" (Experimental Methods for Biomembranes), volume 2, page 185, published by Kyoritu Shuppan Co.).
Each of these prior art methods, however, requires extremely high skillfullness. In addition, the molecular aggregates obtained by these methods are limited to a monolayered vesicle or spherical multilayered vesicle and long fibrous assemblies cannot be prepared thereby. On the other hand, several method are disclosed, for example, in Journal of the American Chemical Society, volume 119, pages 9120-9124 (1997) for the preparation of a fibrous assembly from a synthetic amphiphilic compound in water. Each of these methods, however, is a method in which fibrous assemblies are obtained by spontaneous precipitation or crystallization from a hot concentrated aqueous solution containing an amphiphilic compound so that the yield of the product is necessarily limited.